It Happened One Night   Or Did It?
by VampirePam
Summary: John and Sherlock wake up together in John's bed after a crazy night. Since neither can remember what happened, they are forced on an adventure around London to retrace their steps. But are they ready to accept the consequences of solving this mystery?
1. Then the Morning Comes

The first thing John registered was a tiny drummer playing a percussive staccato against the inside of his skull As he became more awake, however, John was forced to admit that this was perhaps a slightly far-fetched conclusion, and that his symptoms did seem equally consistent with an ordinary, albeit intense headache.

He very reluctantly opened his eyes a crack, and once the light no seemed to be sending knives straight into his brain, he was relieved to be able to make out the familiar, if blurry, shape of his bureau. _Well, made it back to my own room, at least_, John thought with a sigh, _that has to count for something_.

His attempt to get out of the bed with a modicum of grace failed completely, and John soon found himself face to face with the floorboards. A groan escaped his lips as he crawled on his hands and knees toward the bureau, gripping it tightly as he slowly got to his feet.

"Bloody hell," he muttered under his breath as he got a look at his reflection in the mirror. His physician's mind automatically catalogued his visual symptoms: pupils, glassy; complexion, distinctly pallid; eyes, bloodshot; skin, clammy. _Yep_, thought John grimly, _just as I suspected; definitely a hangover._

With his diagnosis complete, John was just about to go about filling his usual prescription of a couple of aspirin, plenty of water, and the greasiest English breakfast he could find when he looked past his own reflection in the mirror and caught sight of someone moving about in the bed behind him.

The part of him that reacted this time was not the doctor, but the soldier, and John instinctively grabbed the first vaguely threatening object in easy reach - in this case, a remote control - before whirling around to face the intruder in his bed.

The occupant of the bed, meanwhile, gave a little groan of his own and turned over, presumably to get away from the light streaming through the window adjacent to the bed. This movement let John get a good look at him, and one glimpse at his visitor's tangle of curly hair and slim, pale torso caused waves of emotion to wash over him in quick succession: first recognition, then relief, then utter horror.

"Sherlock?" John shouted, still brandishing the remote control. "What in God's name are you doing in my bed?"

"John," Sherlock said, his voice pained and impatient, "Our shared affliction cannot have escaped even your notice, and I am going out on a limb and presuming you have at least a cursory knowledge of its symptoms. Consequently, I am quite surprised that I have to even ask that you _please_ be so good as not to shout at me!"

"Sorry," John mumbled automatically, before remembering there were far more pressing matters to be discussed. "No, hang on, you didn't answer my question - why are you in my bed? And, good God," John exclaimed, though he made an effort to keep his vocal volume low, as an infinitely more disturbing question occurred to him mid-sentence, "why are you naked?"

"The answer to the former shall undoubtedly prove more complicated than that to the latter, so I shall pass by it for the moment," Sherlock began, locking his fingers together and folding them over his chest, as was so often his custom when making deductions, but which looked distinctly odd in this particular context.

"Now, as to your second question, I'm afraid that it is unanswerable; once again you have failed to gather all the relevant data before reaching your conclusion, and said conclusion is consequently based on a supposition that is incorrect."

"English, Sherlock," John said through gritted teeth, his battered brain in no condition to sift through Sherlock's typical deductive jargon. "Plain English, if you please."

Sherlock's eyes flew open just enough to fix John with a glare that seemed to be saying, "I cannot believe I have to deal with such pitiful mortals at this hour of the morning," before continuing with an impatient sigh, "Simply put, I cannot tell you why I am naked, John, because I am not naked. On the contrary, a cursory self-examination some minutes ago revealed that, while I am far less...clothed than I am accustomed to being, I am currently wearing my usual undergarments, as well a single sock. In fact, in the realm of attire, I am technically more dressed than you are, my dear doctor."

John's eyes instinctively flew down to his own person, and he was dismayed to discover that, as he was only wearing a pair of knickers, Sherlock had indeed beaten him in that arena, albeit only by a sock. He let out a groan, frustratedly raked a hand through his hair, and asked, though he was not sure if he really wanted an answer, "And as to why you're in my bed...?"

Sherlock's eyes flew open, all the way this time, his brow furrowed, and he said, "Unfortunately, the evidence at my disposal is insufficient for me to answer that question to my personal standard of satisfaction. I have a few working theories - seven, in fact - but I cannot deem any of them to be the final solution until I have more specifics."

"But surely - I mean, _you _of all people have to remember what happened last night."

"You obviously don't," Sherlock shot back a bit defensively, "Why should I?"

"Well, yes, _I _don't," John conceded, "But with your super-brain, I just assumed..."

"My brain is only superior in its cognitive functions and deductive abilities," Sherlock retorted. "It has no superior predisposition for processing an excess of alcohol in such a way as to impede the customary memory loss."

John was prevented from replying by the sound of a pleasant, female voice echoing in from the stairwell, followed by the opening of the bedroom door.

"John, dear? I thought you might like a spot of tea. Just this once, mind you; I'm not your houseke - oh my God!"

Such was the shock she received upon seeing her two tenants together and in such an advanced state of undress - Sherlock in the bed and John by the dresser - that Mrs. Hudson dropped the tray of tea and biscuits she was carrying; it landed on the floor with a crash jarring enough for Sherlock to call out "Mrs. Hudson, _please!"_

John was too preoccupied with finding something - anything - with which to cover himself to react, and after he had quickly grabbed a discarded pillow from the floor and placed it strategically in front of his midsection, he exclaimed, "Really, I am so sorry, Mrs. Hudson!"

"I figured you boys would be in bits this morning after the ruckus you made coming in last night - or should I say this morning -" she accompanied this addendum with a maternal glare made John want to apologize all over again - "but I must say, I wasn't expecting this! What on earth did you two get up to last night?"

"That, Mrs. Hudson," Sherlock said, dragging himself into a sitting position and leaning against the headboard of John's bed, "Is the very thing we are endeavoring to ascertain."


	2. The Butterfly Effect

"Now, then," Sherlock said, looking intently at Mrs. Hudson, "You must tell us everything."

"Oh well..." Mrs. Hudson trailed off, consciously averting her eyes as she bent to return the spilled cookies and overturned teacups to the tray.

"Er, yes" John interjected with a pointed look at Sherlock, "perhaps it would be best if you gave us a moment first, Mrs. Hudson." He began to inch slowly behind the bureau, his eyes wildly searching the room for a more suitable ensemble than underwear and a strategically placed pillow.

"Of course, dear," Mrs. Hudson acquiesced quickly, grabbing the discarded tray and heading for the door. "Why don't I go downstairs and whip you boys up a spot of breakfast? Just this once, mind you," she called out as she made her way down the stairs, and John could just barely make out the words, "not your housekeeper," before she went out of earshot.

The second she was gone, John dove for the bureau, flinging open the second drawer and grabbing the first pair of jeans he saw. "You really don't remember anything?" he asked incredulously as he pulled on the jeans, diverting more attention than should have been necessary into putting first one leg and then the other into the denim. "Not even whether or not we..." John found himself completely unable to finish that sentence in a way that made any sense with his world view of twenty-four hours before.

Sherlock was prevented from responding with anything more than an amusedly arched eyebrow by John being too eager to don the accompanying jumper, moving more quickly than was prudent for one in his state, and consequently getting rather hopelessly tangled in charcoal grey wool.

"Honestly, John," Sherlock's impatient voice filtered in through the jumper, "I really don't understand how you managed to obtain a medical and yet are continually stumped by tasks which primary school children the world over manage daily with little to no difficulty."

Immediately after hearing this, John felt Sherlock's fingers deftly manipulating the jumper into its proper position, working John's hands through the armholes and tugging the bulk of it down over his torso in a matter a few seconds. Before John could say anything in response, whether it be a few words in his defense or a begrudging thank you, Sherlock had already rolled his eyes, let out a snort of derision and pivoted toward the door, striding swiftly in the direction of his own room.

_Only Sherlock could manage to look haughty wearing only knickers and a single sock, _John thought as he watched his flatmate walk away, smiling to himself until he realized that staring at Sherlock's barely clothed retreating form was decidedly _not_ something that should be bringing him enjoyment, especially considering what may or may not have happened the night before.

He quickly shook that thought from his head and focused instead on getting dressed, which apparently required far more attention than usual that morning.

Ten minutes, two extra-strength aspirins, and a few more articles of clothing later, John felt at least moderately prepared to face the world. As he made his way down the stairs, he was somehow not surprised to see Sherlock already seated at the wooden table in the kitchen, his eyes darting methodically over the pages of the Telegraph.

"But Sherlock, dear, you must eat something!" Mrs. Hudson scolded as she busied herself scrambling some eggs. "You shan't be feeling yourself again until you do, I'll tell you that! Why, I remember when Mr. Hudson used to go on a bender -"

"Yes, thank you, Mrs. Hudson," Sherlock interrupted curtly, his eyes continuing to scan the paper, "While I am sure that your undoubtedly top-notch bacon and eggs were of a great comfort to your late husband, they are of little use to me." He unbuttoned one cuff and extended his forearm toward her, and John could see that it was covered by three large nicotine patches.

"As you can see, I am already possessed of all the curatives I need."

"You realize that nicotine is not in an appropriate remedy for a hangover, and may in fact exacerbate its symptoms" John said skeptically, trying to suppress a shudder as he gingerly removed the tarantula habitat occupying the other chair before sinking down opposite Sherlock and burying his still aching head in his arms.

"Yes, well, you'll forgive me if I don't rush to obey the medical advice of a man with a butterfly stamped on his hand," Sherlock said dryly, still leafing through the paper.

"What?" John exclaimed, his eyes instinctively darting downward; to his utter horror, he saw that Sherlock was indeed correct - on his right hand was clearly visible the faded outline of a purple butterfly. "Bloody hell! Where did that come from?"

"Presumably it used to be a purple caterpillar," Sherlock said sarcastically. "Really, John, you must write the scientific journals and tell them you've discovered a new species of the order _lepidoptera _whose metamorphosis is triggered by the consumption of large quantities of alcohol."

Before John could stimulate his battered brain into coming up with an appropriate retort, Mrs. Hudson swept over to him. "Now you must have some of my eggs, dear," she insisted, placing a heaping plate of them on the table in front of him. "They'll do wonders for that head of yours."

John obediently dug into the pile of eggs and was pleased to discover they did, in fact, alleviate the dull throbbing in his skull.

Sherlock, meanwhile, finished flipping through the final few pages of the Telegraph and deposited it triumphantly on the table, declaring, "Yes, all good; Armenia's possible, but it's probably just a routine uprising."

"Are you sure you're feeling all right?" John asked doubtfully, placing a hand on Sherlock's forehead.

Sherlock batted it away impatiently. "I was _merely_ making sure that whatever we got up to last night didn't result in any sort of international incident."

"And Armenia?" John inquired, a little scared of the answer.

"Probably nothing," Sherlock said absently, "the ambassador almost always ignores my texts."

"Oh, well, that's all right, then," John said, throwing up his hands, although he was sure the sarcasm eluded his flatmate.

"With that taken care of, we can move on to other areas of inquiry," Sherlock said decidedly. "Now, then, Mrs. Hudson, what exactly do you remember from last night? Remember, the most seemingly insignificant details may be the most pertinent."

"Oh, well, let me see now..." Mrs. Hudson began, her brows drawing together in concentration. "It must have been three or four in the morning - I'd been having some trouble with my hip, you see, and I'd just taken one of my herbal soothers and settled back into bed when I heard this...din in the hallway.

"What kind of din, precisely?" Sherlock probed inquiringly.

"I remember hearing the door slam open, followed by some muffled voices - I think they were _laughing_. Then there was a crash, some more laughing and shushing, and the sounds of two pairs of feet running very quickly up the stairs."

"How could you tell there were two pairs?" John asked.

"You don't rent a flat to Sherlock Holmes without learning a thing or two," Mrs. Hudson said, crossing her arms proudly.

The corners of Sherlock's mouth quirked up into the hint of a smile. "Anything else?"

"Now that you come to mention it, there was one more thing. Just after the door slammed open - it sounded like someone singing."

"Singing?" John asked incredulously.

"Yes, quite boisterously in fact! How did it go now? Something like," Mrs. Hudson began singing a little to herself, "_Love me, love me, say that you love me._ It was quite off-key, but very sincere. That's really all I recall, dear."

"Yes, thank you, Mrs. Hudson, that was most helpful," Sherlock said briskly before whipping his head round to face John. "John, do you have your mobile?"

John shook his head. "I had an exhaustive look-round before I came down, but there was no sign of it. Yours?"

"Nowhere to be found," Sherlock replied, "so I suppose I'll have to resort to slightly more outmoded methods." With that, he sprung up and sprinted over to the computer.

"Let me see," Sherlock muttered to himself as his fingers dancing gracefully over the keys, "if I narrow by shape, color and probable geographic area...a-ha!"

He immediately leapt up and ran to the foyer to grab his scarf, shouting, "Come, John, there's work to be done!"

"Work?" John asked incredulously. "You cannot seriously be thinking of a case at a time like this!"

"Of course I am, John!" Sherlock exclaimed excitedly, grasping him by the shoulders. "The most thrilling one I've had in months - the case of the missing night!"

"You're not serious!" John exclaimed.

Sherlock stared at him in disbelief. "We finally get our hands on a proper mystery, and you want to, what, sit at home and watch telly?"

"Sherlock, this isn't some logic exercise, these are our lives we're talking about here," John said, exasperated.

"All the more reason to get to the bottom of it, then!" Sherlock responded impatiently, shoving John's arms into his overcoat despite his very vocal objections.

"What's got you so excited, then, Sherlock?" Mrs. Hudson called from the kitchen where she was finishing the washing up.

"Butterflies, Mrs. Hudson!" Sherlock shouted back as he pushed a still protesting John out the front door, "Specifically, purple ones."

"But what does that mean, dear?" Mrs. Hudson asked, confused.

"It means, Mrs. Hudson," Sherlock replied, eyes alight with anticipation, "that the game is on!"


End file.
